We described 4 men aged 29 to 63 years of age who had familial hyperchlomicronemia and lipid deposits on left atrial endocardium. The occurrence of lipid deposits on left atrial endocardium appears to occur only in patients with hyperchlomicronemia but why these deposits at this location occur in patients with elevated serum chylomicrons is unclear. In these 4 men atherosclerosis was absent or minimal despite the lipid deposits on the mural endocardium of left atrium.